skan added a comment. In D70157#1786901 <https://reviews.llvm.org/D70157#1786901>, @reames wrote:
> Noting another issue we found in local testing (with an older version of this > patch). This interacts badly with the implicit exception mechanism in LLVM. > For that mechanism, we end up generating assembly which looks more or less > like this: > Ltmp: > > cmp %rsi, (%rdi) > jcc <target> > > > And a side table which maps TLmp to another label so that a fault at Ltmp can > be interpreted as an extremely expensive branch via signal handler. > > The problem is that the auto-alignment of the fused branch causes padding to > be introduced which separate the label and the faulting exception, breaking > the mapping. > > Essentially, this comes down to an implicit assumption that the label stays > tightly bundled with the following instruction. > > This can happen with either nop or prefix padding. How about insert NOP before the label `Ltmp`? CHANGES SINCE LAST ACTION https://reviews.llvm.org/D70157/new/ https://reviews.llvm.org/D70157 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
